This adds a few lines describing `mux-be` multiplexer configuration
for multiplexing several backend devices with a single frontend
device.
Signed-off-by: Roman Penyaev <r.peni...@gmail.com>
Cc: "Marc-André Lureau" <marcandre.lur...@redhat.com>
Cc: qemu-devel@nongnu.org
---
qemu-options.hx | 78 ++++++++++++++++++++++++++++++++++++-------------
1 file changed, 58 insertions(+), 20 deletions(-)
diff --git a/qemu-options.hx b/qemu-options.hx
index d5afefe5b63c..22490c529a50 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3693,37 +3693,37 @@ DEFHEADING(Character device options:)
DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
"-chardev help\n"
- "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
null,id=id[,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
"-chardev
socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]\n"
- "
[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n"
+ "
[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off][,mux-be-id=id]\n"
" [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID]
(tcp)\n"
"-chardev
socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n"
- "
[,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off]
(unix)\n"
+ "
[,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off]
(unix)\n"
"-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
- "
[,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n"
+ "
[,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off][,mux-be-id=id]\n"
" [,logfile=PATH][,logappend=on|off]\n"
- "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
msmouse,id=id[,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
"-chardev
vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
- " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+ " [,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
"-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
- "-chardev
file,id=id,path=path[,input-path=input-file][,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
- "-chardev
pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
file,id=id,path=path[,input-path=input-file][,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
pipe,id=id,path=path[,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
#ifdef _WIN32
- "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
- "-chardev
serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
console,id=id[,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
serial,id=id,path=path[,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
#else
- "-chardev
pty,id=id[,path=path][,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
- "-chardev
stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
pty,id=id[,path=path][,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
stdio,id=id[,mux=on|off][,mux-be-id=id][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
#endif
#ifdef CONFIG_BRLAPI
- "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
braille,id=id[,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
#endif
#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
|| defined(__NetBSD__) || defined(__OpenBSD__) ||
defined(__DragonFly__)
- "-chardev
serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
serial,id=id,path=path[,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
#endif
#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
- "-chardev
parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev
parallel,id=id,path=path[,mux=on|off][,mux-be-id=id][,logfile=PATH][,logappend=on|off]\n"
#endif
#if defined(CONFIG_SPICE)
"-chardev
spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
@@ -3735,8 +3735,8 @@ DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
SRST
The general form of a character device option is:
-``-chardev backend,id=id[,mux=on|off][,options]``
- Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``,
+``-chardev backend,id=id[,mux=on|off][,mux-be-id=id][,options]``
+ Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``, ``mux-be``,
``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``,
``pty``, ``stdio``, ``braille``, ``parallel``,
``spicevmc``, ``spiceport``. The specific backend will determine the
@@ -3793,9 +3793,10 @@ The general form of a character device option is:
the QEMU monitor, and ``-nographic`` also multiplexes the console
and the monitor to stdio.
- There is currently no support for multiplexing in the other
- direction (where a single QEMU front end takes input and output from
- multiple chardevs).
+ If you need to multiplex in the opposite direction (where one QEMU
+ interface receives input and output from multiple chardev devices),
+ each character device needs ``mux-be-id=id`` option. Please refer
+ to the paragraph below regarding chardev ``mux-be`` configuration.
Every backend supports the ``logfile`` option, which supplies the
path to a file to record all data transmitted via the backend. The
@@ -3895,6 +3896,43 @@ The available backends are:
Forward QEMU's emulated msmouse events to the guest. ``msmouse``
does not take any options.
+``-chardev mux-be,id=id``
+ Explicitly create chardev backend multiplexer with possibility to
+ multiplex in the opposite direction, where one QEMU interface
+ (frontend device) receives input and output from multiple chardev
+ backend devices.
+
+ For example the following is a use case of 2 backend devices: text
+ virtual console ``vc0`` and a socket ``sock0`` connected
+ to a single virtio hvc console frontend device with multiplexer
+ ``mux0`` help. Virtual console renders text to an image, which
+ can be shared over the VNC protocol, in turn socket backend provides
+ biderectional communication to the virtio hvc console over socket.
+ The example configuration can be the following:
+
+ ::
+
+ -chardev mux-be,id=mux0 \
+ -chardev
socket,path=/tmp/sock,server=on,wait=off,id=sock0,mux-be-id=mux0 \
+ -chardev vc,id=vc0,mux-be-id=mux0 \
+ -device virtconsole,chardev=mux0 \
+ -vnc 0.0.0.0:0
+
+ Once QEMU starts VNC client and any TTY emulator can be used to
+ control a single hvc console:
+
+ ::
+
+ # VNC client
+ vncviewer :0
+
+ # TTY emulator
+ socat unix-connect:/tmp/sock pty,link=/tmp/pty & \
+ tio /tmp/pty
+
+ Multiplexing of several backend devices with serveral frontend devices
+ is not supported.
+
``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]``
Connect to a QEMU text console. ``vc`` may optionally be given a
specific size.
--
2.34.1
